(a) Field of the Invention
The present invention relates to a clutch assembly of an automatic transmission, and in particular, to a multi-plate clutch assembly capable of reducing shift shock of the transmission.
(b) Description of the Related Art
FIG. 1 schematically shows a conventional clutch assembly. The clutch assembly 2 comprises a plurality of clutch plates 6 and clutch discs 8 alternately installed in a clutch retainer 4, a snap ring 10 mounted in a distal end portion of the retainer 4 so as to contact a last clutch plate, and a dished plate 14 interposed between a first clutch plate and a piston 12 so as to prevent the clutch plates and discs from abruptly being engaged. A return spring 16 is installed in the retainer 4 for returning the piston 12.
Typically, an automatic transmission is equipped with a wet multi-plate clutch as a gear shift mechanism. A TCU (transmission control unit) determines a vehicle""s conditions on the basis of parameters from various sensors and responsively operates friction elements such as clutches and brakes by controlling valves of a hydraulic mechanism.
The dished plate is an optional element for enhancing the shift quality of the vehicle by providing a smooth engagement and quick disengagement of the clutch assembly.
However, the dished plate occupies a relatively large amount of space, that is, the installment of the dished plate requires 5 mm per clutch set to secure the space for the plate""s thickness and stroke displacement and this increases the transmission size and weight. Furthermore, the adaptation of the dished plate increases the whole manufacturing cost of the transmission because the dished plate is an expensive item.
The present invention has been made in an effort to solve the above problems of the prior art.
It is an object of the present invention to provide a clutch assembly capable of reducing shift shock of an automatic transmission without using additional parts such as a dished plate, which causes increases in the size and weight of the transmission as well as whole manufacturing costs.
To achieve the above object, a clutch assembly of an automatic transmission according to the present invention comprises a clutch drum having a slanted inner surface at a corner formed by circumferentially bending a circumferential edge of the clutch drum, a plurality of friction members alternately arranged in the clutch drum, a piston for actuating the friction members, the piston contacting the friction members, and a cushion ring having a circumferentially slanted outer surface corresponding to the slanted inner surface of the clutch drum, the cushion ring being installed into the clutch drum so as to contact the slanted outer surface of the cushion ring with the slanted inner surface of the clutch drum.